The present invention relates to an endoscope, and more particularly to a bending manipulation device for the endoscope, which is capable of directing the bending portion in the insertion part of the endoscope to the desired direction by turning an angle knob provided in the main control portion of the endoscope.
In general, the endoscope is made up of the main control portion and a flexible insertion portion which is connected with the above operation portion and inserted into an objective body, for instance, a human body and other things, which need observation, inspection, and so forth of their inside. This insertion portion is made up of a flexible soft portion connected with the operation portion, a flexible bending portion connected with the tip side of the above flexible soft portion, and a hard tip distal end portion connected with the tip of the above bending portion and provided with a objective window (lens) or the like necessary for observation, inspection, etc. of the inside of the objective body.
In order to manipulate the above bending portion, the endoscope includes a bending manipulation device in the above main control portion. With regard to the bending manipulation device of this kind, the Japanese patent publication No. 8-82749 has already disclosed that which has such a structure as shown in FIG. 15 of the accompanying drawings attached to this specification. Referring to this figure, a pulley 10 is rotated by means of the angle knob provided in the main control portion of the endoscope. The pulley 10 includes two parallel groves independently prepared for every control wire. Control wires 12, 14 are taken up by two grooves, respectively. The bending manipulation device is constituted such that as the pulley 10 is rotated, one of control wires 12, 14 extending out from the pulley 10 is taken up by the pulley 10 corresponding to the rotation of the pulley 10 while the other is paid out from the pulley 10, thereby enabling the bending manipulation of the bending portion to be carried out.
In order to improve the observation performance of the endoscope, it is desirable to increase or widen the range of the angle that the above-mentioned bending portion is allowed to be curved. In order to achieve this, it is required to increase the wire stroke of the control wire.
There have been proposed certain constitutions for increasing the above wire stroke. One of them, for instance, is to increase the winding diameter of the pulley 10 by which control wires 12, 13 are taken up. However, an increase in the winding diameter of the pulley 10 results in an increase in the rotational torque of the pulley 10, which causes such a problem that the angle knob (referred to simply as xe2x80x98angle knobxe2x80x99 hereinafter) comes to require a larger force for turning it.
There have been also proposed certain constitutions for decreasing the rotational torque of the pulley 10. One of them, for instance, is to decrease the winding diameter of the pulley 10. However, in the constitution like this, the smaller the winding diameter of the pulley 10 is made, the more the angle knob has to be turned more until the bending portion takes the same angle, so that difficulty in handling the endoscope remains. Furthermore, if trying to make the wire stroke still larger, control wires 12, 14 have to be wound more than one turn on the same groove of the pulley 10 as shown in FIG. 15. As a result of that, the winding diameter gradually becomes larger, the torque becomes larger, and operation with constant torque becomes impossible. At the same time, the overlapped control wires come to interfere with each other and rub together, which reduces the durability of control wires.
There have been further proposed certain constitutions for avoiding that one control wire is taken up more than one turn on the same groove of the pulley 10, in other words, a so-called double winding of the control wire onto a single groove. It is one of them, for instance, to form two spiral grooves extending in the axial direction of the pulley 10, each groove being separately used by each of two control wires. According to this constitution, however, the pulley 10 is required to have a width allowing at least a two step groove portions for one control wire to be provided in the axial direction of the pulley 10. As two control wires are used in order to curve the curve portion in the up/down directions, the pulley 10 has to have a width allowing four step groove portions in total. Furthermore, as two control wires have to be added in order to curve the bending portion in the right/left directions, the pulley 10 has to have a width allowing eight step groove portion to be prepared therein. Thus, if adopting a constitution like the above, the pulley 10 must have a larger space in the axial direction thereof, by which the whole weight of the endoscope is increased. Therefore handling the endoscope is more difficult.
The invention has been made in view of such problems as described above, and the principal object of the invention is to provide a novel and improved bending manipulation device for the endoscope, which is capable of preventing the rotational torque from becoming larger at the time of executing the bending manipulation, avoiding interference between control wires, facilitating the miniaturization of the device, and making the stroke of the control wire much larger.
According to the invention, in order to solve problems as described above, there is provided a bending manipulation device for an endoscope which include a pulley provided in and given a rotary motion by the main control portion of the endoscope; at least a pair of control wires, each of which winds one end portion thereof on to the pulley and extends out the other end portion thereof from the pulley such that one of the extended control wires is taken up by the pulley while the other of the same is paid out from the pulley corresponding to the rotation of the pulley, thereby enabling the bending manipulation over the bending portion to be carried out; and at least one common groove formed on the periphery of the pulley to continuously extend in the peripheral direction of the pulley, and commonly used by the pair of control wires for winding themselves thereon.
According to the constitution of the bending manipulation device as described above, various advantageous effects can be obtained as follows. That is, the groove of the pulley for taking up a pair of control wires is formed as a single groove continuously extending in the peripheral direction of the pulley, so that the double winding of each control wire can be avoided. Because of this, it becomes possible to prevent the increase in the rotational torque caused at the time of executing the bending manipulation, and also, to avoid the interference between the same control wires.
Furthermore, each of control wires is alternately taken up on the groove of the pulley corresponding to the turning direction of the pulley. As one of control wires is taken up on the groove, this control wire gradually uses the groove of the pulley. At this time, the other control wire is paid out from the pulley, so that the groove of the pulley comes into the unused state gradually. Consequently, as there is neither the chance that the groove of the pulley is used by two control wires at a time, nor the chance that the control wires interferes with each other.
Still further, as the groove of the pulley is formed as a single groove continuously extending in the peripheral direction of the pulley, each control wire is able to commonly use this groove, so that it becomes possible to make the length of the groove shorter than that used in the prior art case wherein the groove has been provided for each of the control wires. At the same time, it becomes also possible to reduce the number of steps of the groove, whereby the space in the axial direction of the pulley is saved and the miniaturization of the device is facilitated.
Still further, in the bending manipulation device according to the invention, the groove is constituted such that one part from the one end of the groove and the other part from the other end of the same are formed in parallel with each other while each of the control wires is alternately taken up on the groove, so that the stroke of each control wire can be made longer.